The invention is related to the field of graphene and, in particular, to the synthesis and fabrication of large-area graphene films on arbitrary substrates (i.e., any of a wide variety of substrates) and the fabrication of patterned graphene structures based on the synthesis method.
In recent years, research on single- or few-layer graphene (SLG or FLG) has attracted much attention. “Graphene” refers to a single layer of hexagonal carbon structure. Single-layer-graphene and few-layer-graphene structures have been predicted and demonstrated to have many remarkable properties, such as high electron and hole mobilities with a symmetrical electron and hole band structure, high current-carrying capacity, high in-plane thermal conductivity, high tensile strength and high mechanical stability. When graphene is cut into narrow strips, it bears attributes very similar to those of carbon nanotubes, which have been investigated thoroughly. However, there are many hurdles for the application of nanotubes due to the challenges of controlling the nanotube structures, whereas graphene strips or other structures can be patterned by conventional top-down lithography methods, which can be advantageous. The observation of an unconventional quantum Hall effect in graphene has also been reported and can be seen even at room temperature. The linear E(k) relationship in the electronic band structure of graphene gives rise to an unusual massless Dirac fermion behavior of the electrons. The electrical conductance of graphene is also sensitive to the absorption or desorption of even a single gas molecule. Graphene sheets, accordingly, show great potential as another materials option for electronic applications (e.g., for electronic devices, sensors or composite materials).
Though single- and few-layer graphene offer such significant advantages, the current methods for achieving single- and few-layer graphene are very limited. Existing methods include high-temperature vacuum annealing of SiC single-crystal substrates, hydrocarbon decomposition on single crystal metal substrates under ultra high vacuum (UHV) conditions, or manually cleaving highly oriented pyrolytic graphite (HOPG) using adhesive tape on SiO2 substrates. These methods are not well suited for large-scale manufacturing.